What is the area of a square with a side length of 4 units?

To find the area of a square, you use the formula:

[ \text{Area} = \text{side length} \times \text{side length} ]

In this case, the side length of the square is given as 4 units. Thus, you would calculate the area as follows:

[ \text{Area} = 4 \times 4 = 16 \text{ square units} ]

This means that a square with each side measuring 4 units has a total area of 16 square units. The square's area represents the amount of space inside the square, confirming that the dimensions indeed follow the prescribed formula. Therefore, the correct calculation leads to the conclusion that the area of the square is 16 square units.